Can 'favorite' apply even if I don't still program in the language? If so, Euphoria would definitely be my answer. I don't actually code in it anymore, but it was my go-to language for essentially everything for many years, and still would be if it weren't for a handful of things that really have little to do with the core language.
Clean syntax, interpreter ease of development, translate to C compilation for faster run, custom type-checking routines, error messages that actually make sense, that lovely sequence data type, mmmmm
. Euphoria was one of the few languages I felt I could actually 'think' in, it fit me so well.
If the 'favorite' label isn't allowed for a language I don't use anymore, then I guess PureBasic would be my current fav. My feelings about it are kind of like mouser's for C++, though; I like it a lot, but it's still just the thing that meets my goals better than anything else at the moment. I'm still on the lookout for something that will really knock my socks off the way Euphoria did years ago, but no luck so far...